1. Field of the Invention
The present invention relates in general to automatic washing machines using low frequency vibration in clothes washing and, more particularly, to an improved structure in such washing machines for prevention of jamming of clothes in a gap between a low frequency vibrating disc and the inner bottom of a washing tub.
2. Description of the Prior Art
In order to wash clothes in a conventional automatic washing machine using low frequency vibration, a low frequency vibrating disc placed in a washing tub generates a specified low frequency vibration which causes resonance phenomena in a multi-phase washing medium in the washing tub. Here, the multi-phase washing medium consists of water, detergent and air. The level of low frequency is specified in accordance with the shape of the washing tub, the shape of the vibrating disc and the mixing ratio of the multi-phase washing medium.
In the above washing machine, the desired mechanical washing effect is achieved by the micro air bubbles generated by cavitation of the vibrating disc or nonlinear vibration. Both the cavitation and the nonlinear vibration are generated in the multi-phase medium at the same time as the generation of the resonance phenomena. The mechanical washing effect caused by the cavitation or the nonlinear vibration cooperates with a chemical washing effect caused by the detergent in the washing medium, thus to achieve the desired washing effect.
With reference to FIG. 1, there is shown a typical automatic washing machine using the low frequency vibration. The washing machine generally comprises a washing tub 1 receiving a multi-phase washing medium therein, a low frequency vibrating disc 2 causing the resonance phenomena in the washing medium and a disc drive unit 3. The vibrating disc 2 is placed in the washing tub 1 and driven by the drive force of the drive unit 3.
It has been noted that the above washing machine is profitable from the viewpoint of energy savings since it requires minimum energy for generation of the resonance phenomena in the multi-phase washing medium in the washing tub 1. However, this washing machine has a problem in that some of the clothes are often jammed in a gap between the vibrating disc 2 and the inner bottom of the washing tub 1. Such a jamming of the clothes causes damage to the jammed clothes. The jammed clothes also prevent other clothes from circulating in the washing medium in the tub 1, thus deteriorating the washing effect of the washing machine.